Rolling codes are known in the art. Rolling codes are often used, for example, in conjunction with movable barrier operators of various kinds (with movable barrier operators of various kinds also being known in the art and including operators that effect the selective control and movement of single panel and segmented garage doors, pivoting, rolling, and swinging gates, guard arms, rolling shutters, and various other movable barriers). In such an application setting, a wireless transmitter can send a code to a corresponding movable barrier operator to cause the latter to effect a desired movement or other action with respect to, for example, a corresponding movable barrier.
When using rolling codes, the code transmitted by the wireless transmitter will change (often with each transmission) in accordance with a predetermined plan or algorithm that is also known to the movable barrier operator. Such an approach can foil the use of an intercepted code by an unauthorized party because that intercepted code will not typically again, at least in the near term, be honored by that movable barrier operator should the unauthorized party attempt to themselves transmit that code. Without knowledge of the underlying scheme by which a next code is selected, the unauthorized party who gains access to a presently used code will still remain unable to leverage that knowledge in support of effecting unauthorized control over the movable barrier operator.
There may be instances, however, when additional security may be desired or appropriate. For example, a given rolling code instantiation may be open to brute force attacks or other weaknesses due to local and/or otherwise unique circumstances.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein.